Sunspots - Sunspots are cooler areas on the surface of the Sun. Because they are "cooler" than the surrounding areas they appear darker. Sunspots are 3,000 degrees Celsius cooler than the rest of the Sun, but they are still a very hot 3,000 degrees Celsius. Sunspots have a varying lifetime; they can last from a few days to a few months. While their sizes vary they can be as large as 50,000 kilometers but can also be a comparatively small 2,000 kilometers. When a sunspot disappears on the western limb of the Sun it will reappear on the eastern limb in about two weeks. A sunspots entire rotation period around the Sun is about 25 days at the equator and 35 days at the poles and 27 in between; this is because plasma at the equator moves quite a bit faster than at the poles.
Science has yet to learn exactly what sunspots are. They are neither holes in the Sun nor peaks of plasma "mountains". They may be areas of magnetic activity. The magnetism affects the heating process and produces cool spots. Sunspots may be as large as Earth and last from days to weeks. One recorded sunspot lasted eighteen months.
|"Yea, the stars are not
pure in his sight."
- The Bible
Though Chinese annals tell of a phenomena on the Sun that we now know is sunspots; the first recorded scientific observation was in 1610 by Galileo. He first observed them while looking at the Sun with his new telescope. Daily sunspot observations and readouts of sunspots were started in 1749 and have continued to supply a constant source of information to scientists ever since. This information has led scientists to conclude several things. One of them is that the number of visible sunspots has approximately an 11-year cycle.
Sunspots have two parts: the darker inner part is named the umbra and the brighter outer part is referred to as the penumbra. Sunspots often occur in pairs; one at the magnetic north pole and one at the magnetic south pole. The magnetic field of a sunspot is 1,000 times greater than the Sun's ordinary magnetic field. The eleven year cycle of sunspots has been repeatedly observed since Galileo's first observations with very little fluctuation either way.
Sunspots have an immense effect on Earth. Although sunspots themselves produce only minor effects on solar emissions the magnetic activity that accompanies the sunspots can produce dramatic changes in the ultraviolet and soft x-ray emission levels. These changes over the solar cycle have important consequences for the Earth's upper atmosphere and weather. There is even a connection between sunspots and the number of auroras in the night skies as shown by the following graph.
©Copyright 1998 Elizabeth
Beckett, Holly Bernitt, and Vishwa Chandra.